Your engine relies upon its air filter to keep dust and debris out of the engine. By providing a clean stream of air to the engine, an air filter ensures the engine gets the right amount of air needed to operate at its peak level.
Worn or dirty air filters will cause your engine to perform poorly; among the things you'll notice is that you’ll have less power and weaker acceleration. Your throttle response will be diminished as well. But how do you know if it’s time to replace your air filter?
One rule of thumb is to keep track of how long your air filter has been in place. The average recommended length of service is about 10,000 to 15,000 miles, which for most people is every year or so. But keep in mind that, as with most things related to your car, this is just a recommendation and it doesn’t take into account your individual driving situation.
If you’re driving in heavy traffic on a regular basis, your air filter is not going to last as long. You’re going to have a lot of stop-and-start driving, which places more demands on your car and will also cause your air filter to get dirtier faster. Driving in dusty or rural locations can also make your air filter’s performance decline more quickly, so keep in mind that where you’re driving will affect how long it lasts.
Knowing some of the telltale signs of a dirty or clogged filter can keep you from waiting too long to replace it. Here are five things to look for that might indicate it’s time for a new air filter.
1) Your Air Filter Looks Dirty
If you know where your air filter is located (you can consult your owner’s manual to find out where to look), you can do a visual inspection. If your air filter is clean, it should be white or off-white. Over time, as dust and dirt accumulate on it, the air filter will get darker and the dirt will be noticeable. When it starts looking dark and grimy, you might be due for a replacement.
2) Your Car Seems to Have Less Power
A clean air filter will help your engine perform better; on newer cars, it can increase acceleration by as much as 11%, and on older cars it can improve mileage by as much as 14%. Other signs that your air filter is affecting your car’s performance is a jerking movement when you accelerate — or by not responding as well as it should.
3) Your Check Engine Light Comes On
There are many different reasons that your check engine light comes on; it can be as simple as a loose gas cap or it can signal a bigger problem. One of those reasons can be that the engine isn’t getting enough air, so carbon deposits form in the engine and that triggers the light on your dashboard. When you take your car in to your mechanic, they’ll be able to do a quick scan to see what’s causing the problem and can tell you if it’s an air filter issue.
4) Your Car Starts Making Strange Sounds
Without enough air, your car’s engine isn’t going to sound like it should. If it’s coughing and sputtering, or if it vibrates excessively when you turn over the engine, there’s a good chance it’s begging for a new air filter. If you notice strange sounds specifically when your car is idling, you may have what's known as "rough idle." Read our topic on this to learn what causes rough idle and possible fixes.
5) Smoke or Flames Shoot Out of Your Exhaust When You Start the Car
One good indication that the air filter needs replaced is the presence of black smoke coming from your exhaust pipe(s) when you fire up the engine. You also might hear a popping sound or see a flame at the end of the exhaust pipe. This can happen when there’s not an adequate supply of air in the engine. Not all of the fuel will burn properly in the combustion cycle and it will leave the car through the exhaust. The flame occurs when the heat of the exhaust ignites the fuel in the tailpipe. If you’re noticing this happening in your vehicle, you should take it to your mechanic immediately, as it can create an unsafe situation.
How Long Will It Take?
Getting your air filter replaced is usually a pretty simple and straightforward procedure and can be done in just a few minutes. That’s especially true in older vehicles. Some manufacturers of newer model cars have changed the design of the engine to make more efficient use of space, and sometimes that means putting air filters in places that are harder to reach—which can slow down the process.
However, your mechanic can usually tell you about how long it will take, and can check it during an oil change.
Getting your air filter replaced can be part of an overall tune-up service that will help you get better mileage and performance from your vehicle. It’s also a great way to catch any minor issues that can be resolved before they become bigger issues.